ML20203M369

NRR E-mail Capture - Cooper - Final RAI License Amendment Request for Approval of EAL Scheme Change (EPID L-LLA-2020-0028)

ML20203M369
Person / Time
Site:	Cooper
Issue date:	07/21/2020
From:	Thomas Wengert NRC/NRR/DORL/LPL4
To:	Dewhirst L Nebraska Public Power District (NPPD)
Wengert T
References
L-LLA-2020-0028
Download: ML20203M369 (6)

Text

From: Wengert, Thomas Sent: Tuesday, July 21, 2020 10:01 AM To: Dewhirst, Linda R.

Cc: Van Der Kamp, David W.; Forland, Thomas J.; Dixon-Herrity, Jennifer

Subject:

Cooper - Final RAI RE: License Amendment Request for Approval of EAL Scheme Change (EPID L-LLA-2020-0028)

Attachments: CNS - Final RAI Concerning EAL Scheme Change LAR.pdf On July 17, 2020, the U.S. Nuclear Regulatory Commission (NRC) staff sent Nebraska Public Power District (NPPD) the draft Request for Additional Information (RAI) identified below. This RAI relates to the license amendment request dated February 18, 2020, that NPPD submitted to the U.S. Nuclear Regulatory Commission (NRC) for approval of an emergency action level (EAL) scheme change for the Cooper Nuclear Station.

On July 20, 2020, the NRC and NPPD staffs held a conference call to clarify the draft RAI. At the conclusion of the call, NPPD informed the NRC staff that the information requested was understood and that no additional clarification of the RAI was necessary. A publicly available version of this final RAI (attached, with minor typographical edits corrected and Draft removed) will be placed in the NRCs Agencywide Documents Access and Management System (ADAMS). As agreed, please provide a response to this RAI within 30 days of this correspondence.

From: Wengert, Thomas Sent: Friday, July 17, 2020 8:24 AM To: Dewhirst, Linda R.

Cc: Van Der Kamp, David W. ; Forland, Thomas J. ; Dixon-Herrity, Jennifer

Subject:

Cooper - Draft RAI RE: License Amendment Request for Approval of EAL Scheme Change (EPID L-LLA-2020-0028)

By letter dated February 18, 2020 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML20055D877), Nebraska Public Power District (NPPD) submitted a license amendment request to the U.S. Nuclear Regulatory Commission (NRC) for approval of an emergency action level (EAL) scheme change for the Cooper Nuclear Station (CNS).

The NRC staff reviewed the submittal and determined that additional information, as described in the attached request for additional information (RAI), is required for the staff to complete its review of this application. This RAI is identified as draft at this time to confirm your understanding of the information that the NRC staff needs to complete the evaluation. If the request for information is understood, please respond to this RAI within 30 days of the date of this request.

Please contact me if you would like to set up a conference call with the NRC staff to clarify this request for information.

Tom Wengert Project Manager - Cooper Nuclear Station NRR/DORL/LPL4

(301) 415-4037 Hearing Identifier: NRR_DRMA Email Number: 687 Mail Envelope Properties (SA9PR09MB592067F3531910CB859870D88F780)

Subject:

Cooper - Final RAI RE: License Amendment Request for Approval of EAL Scheme Change (EPID L-LLA-2020-0028)

Sent Date: 7/21/2020 10:01:25 AM Received Date: 7/21/2020 10:01:25 AM From: Wengert, Thomas Created By: Thomas.Wengert@nrc.gov Recipients:

"Van Der Kamp, David W." <dwvande@nppd.com>

Tracking Status: None "Forland, Thomas J." <tjforla@nppd.com>

Tracking Status: None "Dixon-Herrity, Jennifer" <Jennifer.Dixon-Herrity@nrc.gov>

Tracking Status: None "Dewhirst, Linda R." <lrdewhi@nppd.com>

Tracking Status: None Post Office: SA9PR09MB5920.namprd09.prod.outlook.com Files Size Date & Time MESSAGE 2317 7/21/2020 10:01:25 AM CNS - Final RAI Concerning EAL Scheme Change LAR.pdf 153646 Options Priority: Normal Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:

REQUEST FOR ADDITIONAL INFORMATION LICENSE AMENDMENT REQUEST EMERGENCY ACTION LEVEL SCHEME CHANGE NEBRASKA PUBLIC POWER DISTRICT COOPER NUCLEAR STATION DOCKET NO. 50-298 By letter dated February 18, 2020 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML20055D877), Nebraska Public Power District (NPPD) submitted a license amendment request to the U.S. Nuclear Regulatory Commission (NRC) for approval of an emergency action level (EAL) scheme change for the Cooper Nuclear Station (CNS). The NRC staff reviewed the submittal and determined that additional information is needed to complete the review, as indicated in the requests for additional information (RAIs) below.

Regulatory Requirements/Background The requirements of Section 50.47(b)(4) to Title 10 of the Code of Federal Regulations (10 CFR) state, in part, that:

A standard emergency classification and action level scheme, the bases of which include facility system and effluent parameters, is in use by the nuclear facility licensee...

The most recent industry EAL scheme development guidance is provided in the Nuclear Energy Institute (NEI) document NEI 99-01, Development of Emergency Action Levels for Non-Passive Reactors, Revision 6 (ADAMS Accession No. ML12326A805). %\OHWWHUGDWHG0DUFK 2013, the NRC endorsed NEI 99-01, Revision 6, as acceptable generic (i.e., non-plant specific) EAL scheme development guidance. NPPD proposed to revise the current CNS EAL scheme to one based on NEI 99-01, Revision 6.

The proposed threshold value for AA2.1 is not consistent with the guidance provided by NEI 99-01, Revision 6. NPPD proposed replacing uncovery of irradiation fuel with imminent uncovery of irradiated fuel. CNS provided that the term imminent is consistent with the basis document. Although the term imminent is used in the basis document, it is used in reference to imminent damage rather than imminent uncovery.

Please provide further justification for the use of imminent in the threshold value for AA2.1. This discussion should address CNSs ability to accurately determine whether irradiated fuel is uncovered or not, as well as providing a clarification as to what imminent specifically means as applied to uncovery of irradiated fuel.

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The proposed loss of the Fuel Clad (FC) Barrier threshold value FC3 is drywell radiation monitor (RMA-RM-40A/B) [greater than or equal to] 3.6E+3 Rem/hour. The current FC loss threshold value for the drywell radiation monitor is 2.5E+3 Rem/hour, which is consistent with emergency operating procedure (EOP) indications that core damage is occurring due to loss of core cooling based on drywell radiation monitor reading above 2.5E+3 Rem/hour during a loss-of-coolant accident. The drywell radiation monitor value of 2.5E+3 is not expected to change when CNS implements Revision 4 of the Boiling Water Reactor Owners Group Emergency Procedure and Severe Accident Guidelines (EPGs/SAGs).

NEI 99-01, Revision 6, Section 4.7, EAL/Threshold References to AOP [abnormal operating procedure] and EOP Setpoints/Criteria, provides that several EALs and fission product barrier thresholds may be drawn from a plants AOPs and EOPs to maintain good alignment between operational diagnoses and emergency classification assessments.

Please provide a justification for changing the threshold value for FC3 to one that is not aligned with the current EALs or with the values in the CNS EOPs.

The proposed FC Barrier Potential Loss FC2 and Reactor Coolant System (RCS) Barrier Loss RCS1 threshold values include a parenthetical reference that RPV [reactor pressure vessel]

Flooding required. The CNS EAL Comparison Matrix provides that RPV Flooding required was added to emphasize that this condition is consistent with interpretation in the CNS EOPs. The NRC staff could not determine if the addition of RPV Flooding required was intended to modify the threshold values for FC2 and RCS1 such that a declaration would be made only when RPV Flooding was required or if a declaration should be made whenever RPV water level cannot be determined.

Please explain how the addition of RPV Flooding required to the threshold values for FC2 and RCS1 will not delay or otherwise impact EAL assessment for conditions where RPV level cannot be determined.

The proposed Primary Containment (PC) Barrier Potential Loss PC1 threshold value of PC Flooding is required may not be appropriate for licensees that have implemented EPGs/SAGs Revision 4, as primary containment flooding is less of a preferred option early in the severe accident progression and, in some cases, may not be directed. Additionally, considering that EPGs/SAGs Revision 4 actions may be effective in cooling core debris for some time after SAG entry, using SAG entry as a threshold value may result in an early, and potentially unwarranted, EAL declaration.

Please provide a threshold that is both tied to an operationally significant precursor within the SAGs and is a precursor to a potential loss of containment.

2

The proposed CNS threshold values for EALs SU6.1, SU6.2, SA6.1, and SS6.1 include the condition as indicated by reactor power > 3% ... The Basis discussions for SU6.1 and SU6.2 state:

A successful scram has occurred when there is sufficient rod insertion from the trip of RPS to bring the reactor power to or below the APRM [Average Power Range Meter] downscale setpoint of 3%.

The guidance of NEI 99-01, Revision 6, for the corresponding EALs SU5, SA5, and SS5 provide that a reactor shutdown is determined in accordance with applicable EOP criteria. Current Boiling Water Reactor EPGs typically use either an assessment that all but one control rod has fully inserted or that the reactor is shutdown under all conditions. Although the NRC staff understands that a condition where a reactor power greater than 3% and any reactor protective setpoint is exceeded represents EOP flowchart entry condition(s), the NRC staff could not verify that reactor power was the only EOP flowchart condition that would be used to determine if an Anticipated Transient Without Scram (ATWS) had occurred.

The NRC staff notes that the reactor protective system is designed to place the reactor in a subcritical position. As such, relying solely on an indication of 3% power is not indicative of a failure of an automatic or manual scram failing to shut down the reactor.

Please provide justification for using a reactor power of 3% or below as the only indication of a successful reactor scram. Note: the indication(s) of a successful reactor scram should be consistent with the EOP flowchart conditions that are used to determine whether an ATWS has occurred.

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